/Engine/Source/Runtime/Slate/Public/Widgets/Docking/SDockTab.h
Set the custom code to execute for saving visual state in this tab. e.g. ContentBrowser saves the visible filters.OnExtendContextMenu
void SetOnPersistVisualState ( const [FOnPersistVisualState](API\Runtime\Slate\Widgets\Docking\SDockTab\FOnPersistVisualState) & Handler )